- Preparing the board for painting
- What paint is suitable
- Compositions for outdoor and indoor use
- Preparation and application of paint
- Slab splitting
- Caring for painted OSB
Chipboards create a sufficiently high-quality basis for finishing: they have high adhesion and a moderately pronounced texture. Today you will learn why it is important to choose the right composition for interior and exterior work, as well as how to carry out the work yourself so that the finish retains its appearance for many years..
Preparing the board for painting
The main difficulty in painting OSB (and especially OSB-3 and OSB-4) is their high moisture resistance. It is quite difficult to find a suitable composition, although, on the other hand, the material does not require additional hydrophobization.
Typically, if the board is kept under natural atmospheric conditions for several months, it naturally develops porosity sufficient to absorb even common water-based paints. At the same time, the structure of the material practically does not suffer, and all further surface preparation consists only in sanding until a noticeable roughness appears.
Plates with increased moisture resistance (grades 3 and 4), which have pronounced hydrophobic properties, must be carefully sanded before removing the wax gloss and subsequent priming. For the treatment of moisture-resistant boards before painting, acrylic primers are used, which have the highest adhesion. If a non-water-based paint is subsequently used, it can be primed with polyurethane varnish or drying oil.
Primer paints based on synthetic resins, as well as priming compositions containing a finely dispersed filler, have proven themselves well. To prepare moisture-resistant OSB for painting, look for compounds used for priming surfaces for applying mosaic and textured plasters.
Chipboards can also be pretreated with fire retardants and antiseptic compounds. Such processing does not contribute to a significant improvement in adhesion, but can be performed in accordance with the technical requirements for the object under construction. Note also that the surface quality of the boards varies from one manufacturer to another. In the absence of grinding, large chips and shavings may peel off; such defects must be eliminated before painting..
What paint is suitable
The choice of paint depends entirely on the type of boards being processed. In this regard, the most versatile plates are those with no or moderate resistance to wetting. In practice, even budget options for water-dispersion paints based on acrylic or PVA are well recommended. They have good hiding power, but the consumption can be up to 50% higher than plywood or wood due to the presence of large pores on the surface..
In general, it is believed that the paint must necessarily have a polymer base for processing a particle board and a conventional aqueous emulsion is poorly suited for this. Compositions containing acrylates will make the coating amenable to washing and cleaning, and if it is necessary to provide additional protection from moisture, materials on a latex, alkyd or polyurethane base are used.
The specificity of OSB staining lies in their strongly pronounced texture. The paint spreads on the edges of the protruding chips, and therefore two or even three applications in a row may be required for a continuous coating. However, sometimes it even plays into the hands: the use of tinted compositions in several layers allows you to achieve interesting visual effects.
Multicolor coating and toning is possible mainly for slabs with at least some pronounced moisture absorption. On the other hand, the high aesthetics of the coating is important, as a rule, in interior decoration, where, in fact, boards are mainly used in classes 1 and 2. If you are dealing with a moisture-resistant board, use enamels based on chemical solvents: alkyd, oil, polyurethane paints and varnishes.
Compositions for outdoor and indoor use
One and the same coloring composition cannot be used for interior decoration and on the facade. The first and most important factor is environmental friendliness, because in paint for outdoor work the maximum permissible concentration of potentially hazardous substances is much higher.
The technical side of the issue also imposes its own limitations. The facade coating must have a high vapor permeability and at the same time, prevent direct contact of the slab with water. There are enough examples when insufficient localization of wood sheathing caused accelerated development of mold or mildew, or the use of inappropriate paint resulted in severe warping of the boards..
Therefore, for external finishing of slabs without pronounced moisture resistance, facade compositions should be chosen that correspond to a certain type of structure. In general, paints used in the wet facade system, as well as paintwork materials based on (or containing) silicone and latex, are optimal..
If the facade is arranged with moisture-resistant plates (including SIP-panels with a polystyrene core), then the struggle for vapor permeability is no longer at the forefront and it is possible to use paints that form an impermeable film. Alkyd enamels and varnishes are examples of the most durable coatings.
The simplest material for painting OSB on walls and floors indoors is acrylic paint, which gives a uniform tone and a continuous texture coating. For the implementation of design delights, you can use a stain followed by strengthening with vinyl or polyurethane varnish, or compositions for patination, but always with the subsequent fixation of viscous paintwork materials on polymer binders. The decorative benefit from this treatment is especially noticeable when finishing ceilings..
Preparation and application of paint
When painting OSB, it is better to apply paint and varnish materials in two layers. The first is diluted with the addition of 10–15% of the appropriate solvent. It can be water, acetone or petroleum solvents, depending on the paint composition. The second layer is applied with solid paint.
Water-dispersed acrylic and latex paints have good spreading and therefore, even when applied with a brush, streaks and streaks do not remain on them. It is desirable to apply more viscous polyurethane and alkyd coatings with a roller. Typically for OSB, painting them from a spray gun helps to reduce consumption, which is very important for expensive patina or high-quality stains used in interior decoration.
There is a significant difference in whether slabs are painted before or after fixing. In the latter case, it is imperative to paint the seamy plane, otherwise uneven moisture will inevitably warp the slab. On the other hand, painting already installed slabs is characterized by lower consumption, but such a cladding is inferior in moisture resistance, especially given the lack of protection at the ends.
When painting OSB, it is very important to adhere to the strategy of applying a large number of thin layers, no matter how great the temptation is to smooth out roughness with a thick layer of thick paint. In the latter case, uneven absorption and, as a result, paint peeling is possible, especially when working with boards of class 3 and 4..
The most difficult thing in the decorative finishing of OSB is the high-quality processing of the joints of the plates. If the general filling of the plane is not planned, the seams will inevitably be visible: even if you reinforce them with carbon fiber on synthetic mastic and putty, there will still be a noticeable difference in texture.
That is why it is customary to cover the ends with strips, masking the joints. This, however, may not be entirely appropriate if the order of patching the sheets has not been thought out in advance. Be also prepared that in order to avoid the formation of a large number of disordered joints, the consumption of plates will have to be increased by 15-20%.
The parts of the veining are fixed, as a rule, after painting the main plane. Cover strips stand out favorably against the general background, often they are separately painted in colors that contrast with the rest of the surface. As overlays on the seams, you can use both wooden planks, sewn with brushed nails without hats, and foam “stucco” or flat moldings fixed on plastic silicate glue.
Caring for painted OSB
If a high quality paint was chosen and the application was made in several layers in accordance with the staining technology, the surfaces will be easy to clean and will not lose their attractive appearance over time. For preventive purposes, you can renew the coating every 4–5 years with a fresh layer of varnish or paint diluted to translucency.
Due to the settlement of the building, it is possible for the slabs to peel off over time, in this case it is better to completely tear off the strips and fix them again, hiding the traces of old fastenings with putty. You can repaint OSB almost an unlimited number of times, the main thing is not to apply an unnecessarily thick layer and pre-treat the surface mechanically, improving adhesion.